1. Field
This art relates to an optical module to be used for optical communication. For example, the optical module can implement stable operations of the optical module by allowing efficient heat radiation of an optical transceiver part.
2. Description of the Related Art
In recent years, increases in speed and density of optical modules to be used for optical communication have been greatly advanced. The increases in speed and density of optical modules can contribute to increases in speed and sophistication while making the measures for the heat-radiation of the optical modules difficult. This is because the increase in speed increases the power consumption of parts installed in an optical module and greatly increases the amount of generated heat and the decrease in size optimizes the layout of parts to the limit, which prevents the sufficient allocation of the space for the heat radiation.
The technology for suppressing the increase in temperature of an optical module is disclosed in Japanese Laid-open Patent Publication No. 2003-198026 (Patent Document 1), for example. The technology disclosed in Patent Document 1 suppresses the increase in temperature of an optical module by sandwiching a radiating material between an electronic substrate that may control the optical module, for example, and the cabinet of an electronic machine in the electronic machine to which the optical module is attached, which allows the transmission of the heat generated by parts on the electronic substrate to the optical module.
However, the technology disclosed in Patent Document 1 may not be a measure for the heat radiation of an optical module itself. A technology that allows stable heat radiation of an optical module itself is being strongly demanded since an optical transceiver part that exchanges optical signals in the optical module has a temperature-dependent characteristic.
FIG. 9A is a diagram showing an example of the configuration of a conventional optical module. An optical module 10 shown in the figure includes a housing 101a and a cover 101b so as to form a case, an electronic substrate 102, an optical transceiver part 103, a fixing member 104, a screw 105 and a silicon sheet 106.
The housing 101a and cover 101b are a case for protecting parts installed in the optical module 10. The electronic substrate 102 is a driving circuit for the optical transceiver part 103. The optical transceiver part 103 is a part that performs one or both of the transmission and reception of an optical signal to be used for optical communication and includes a laser element and/or a photodiode, for example. The optical transceiver part 103 connects to an optical fiber for optical communication through an optical connector 20.
The fixing member 104 is a member for fixing the optical transceiver part 103 to the cabinet 101a and is screwed to the cabinet 101a with the screw 105 with the optical transceiver part 103 between the fixing member 104 and the cabinet 101a. The silicon sheet 106 is a sheet of silicon between the optical transceiver part 103 and the cabinet 101b. 
FIG. 9B is a diagram showing the optical transceiver part 103, which is viewed from the direction of the point of vision V1. As shown in the figure, the silicon sheet 106 is in contact with the optical transceiver part 103 in a wide area. Furthermore, since silicon has a better thermal conductivity of 5 W/K*m, the silicon sheet 106 efficiently transfers the heat caused in the optical transceiver part 103 to a radiating point 101c on the cabinet 101b, which suppresses the increase in temperature of the optical transceiver part 103.
However, the conventional optical module 10 has problems that the optical axis may be displaced and/or that the optical transceiver part 103 may be damaged. In order to sufficiently radiate the heat caused in the optical transceiver part 103, the silicon sheet 106 must be tightly in contact with the optical transceiver part 103 and the cabinet 101b, and the silicon sheet 106 must be as thin as possible. For that reason, the cabinet 101b must be assembled into the cabinet 101a with high pressure such that the silicon sheet 106 can be pressed against the optical transceiver part 103 strongly.
For example, if the silicon sheet 106 is a general silicon sheet with an Asker-C hardness of about 30, the pressure of about 0.25 MPa must be applied thereto for a compression rate of 20%. The permissible pressure against an optical transceiver part such as the optical transceiver part 103 is about 65 kPa, and the pressure above is much higher than the permissible pressure. Therefore, the pressure for assembling the cabinet 101b into the cabinet 101a may sometimes damage the optical transceiver part 103.
Even when the optical transceiver part 103 is not damaged, the pressure for assembling the cabinet 101b into the cabinet 101a may move the optical transceiver part 103 fixed at an optimum place by adjusting the optical axis in advance and displace the optical axis, which may cause insufficient optical transmission power and/or a serious problem like the disability of transmission/reception of optical signals.